Issue

Philips, E Ink launch world into paperless era with pliable LCD

02/01/2004

By MARK A. DeSORBO

AMSTERDAM—Purveyors of paper may potentially be perturbed once Philips Electronics starts mass-producing a slim, book-sized panel that will let consumers download newspapers, magazines and other print media.

The Dutch firm announced in late January that it was preparing to manufacture the 5-inch display, which can show detailed images and be rolled up into a pen-sized holder. If connected to a mobile phone, it can also be used to download Web pages, a book, or e-mail.

"We can produce this in batches," says Bas van Rens, general manager of Philips' polymer division. "It's no longer a research project. We're going to build a pilot line that should be ready in 2005 to make one million displays a year.

Researchers at E Ink Corp. show the elasticity of the flexible transistors that are at the heart of paper-like pliable LCDs being introduced by Philips Electronics.

Click here to enlarge image

Philips says it has created the displays using electronics circuits made of plastics, which power a monochrome display created in the ISO Class 4 and ISO Class 6 cleanrooms of E Ink Corp., a privately-held company based in Cambridge, Mass.

"Philips is our manufacturing partner," says Michael McCreary, E Ink's vice president of research and development. "We've been working on this with them for some time, and from a cleanroom standpoint,all of the existing equipment is based on rigid infrastructure. But this will spawn the introduction of flexible, organic transistors. This will enable new manufacturing applications."

The cleanliness level, McCreary says, will not be any different than it is for a semiconductor operation. "The only issues are temperature because too much heat will melt, burn or deform the plastic," he adds. "So, you need low temperature processes, and you're getting away from doping silicon."

The display—the next generation of an existing E Ink technology—consists of a front portion that switches according to electronic signals and a back component circuit made of transistors that control each individual pixel that composes the display.

To function, each pixel needs a circuit behind it, made of transistors. To make electronic paper, the transistors have to be made on a very thin and flexible substrate.

The first generation was a thin-film transistor with a traditional glass backing, which is rigid, McCreary explains. That display is made with a metal foil back pane, which is about three-tenths of a millimeter, or five to 10 times thinner than a traditional LCD.

The other integral part of the display, he says, is the electronic ink, which is made up of millions of tiny microcapsules about the diameter of a human hair. Each microcapsule contains positively charged white particles and negatively charged black particles, which are suspended in a clear fluid.

When a negative electric field is applied, white particles move to the top of the microcapsule where they become visible. This makes the surface appear white at that spot. An opposite electric field pulls the black particles to the bottom of the microcapsules where they are hidden. By reversing this process, the black particles appear at the top of the capsule, making the surface appear dark at that spot.

Philips, Europe's largest maker of consumer electronics and lighting, has already shown prototypes of a glass-based E Ink display, which it says will be in stores later this year.The price has not yet been set, but Philips said it would be in the range of current thin glass models. The new range will use much of the manufacturing technology already being used to make glass-based thin screens, but is more adaptable to different surfaces, such as the dashboard of a car.